Field of the Invention
The invention relates to a winding for a transformer or a coil having a ribbon electrical conductor and having at least one ribbon insulation material layer that is fitted to the electrical conductor or is applied as ribbon material to the conductor, which, that is to say, the electrical conductor and the at least one ribbon insulating material layer, are wound to form turns (also referred to as windings) around a winding core along a winding axis, with the individual turns of the winding have a predetermined winding angle with respect to the winding axis of the winding core. Moreover, a number of turns that are located axially alongside one another form one layer, and at least two radially adjacent layers of turns are provided.
In generally available windings such as these for transformers or coils with a rating of more than 5 kVa, the turns are normally wound such that they lie closely alongside one another in the axial direction, thus, forming a layer of turns. However, frequently, a number of layers are also radially joined to one another and form a multilayer transformer or a multilayer coil. Where there are a number of radially adjacent layers of turns, the winding direction of the electrical conductor in one layer must be reversed at its axial end.
If the widths of the electrical conductor are comparatively narrow, the reversing process can be carried out by changing the winding angle at the axial end of the relevant layer continuously to a value of 90xc2x0, and by finally, for example, after a further half turn, changing it to the desired winding direction. Firstly, this has the disadvantage that a layer is radially thickened at the ends, and, secondly, if the conductor ribbons are comparatively broad, there is a risk of waves being formed, and of kinks being formed in the conductor ribbon. These disadvantageous effects can be further exacerbated if the conductor ribbon is comparatively thin.
In addition, comparatively large winding angles, such as those that occur by way of example in the case of windings around a comparatively small winding core, likewise promote the disadvantageous effects described initially.
It is accordingly an object of the invention to provide a winding for a transformer or a coil and method for producing the winding that overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and, in which, radially adjacent layers of turns can be produced in a simple manner, particularly in the case of those electrical conductors that have a tendency to the disadvantageous effects described initially.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a winding for one of a transformer and a coil, including a winding core having a winding axis, a ribbon electrical conductor, at least one ribbon insulation material layer one of fitted to the electrical conductor and applied as ribbon material to the electrical conductor, the at least one ribbon insulation material layer having a longitudinal direction, the electrical conductor and the at least one ribbon insulating material layer being wound to form turns around the winding core along the winding axis, the turns forming at least two radial adjacent layers, a number of the turns located axially alongside one another forming one of the layers, individual ones of the turns having a predetermined winding angle with respect to the winding axis, a first layer of the turns being radially adjacent to a second layer of the turns, the second layer having a changed winding direction by a folding of the electrical conductor and the at least one ribbon insulating material layer, and a total angle of the folding between the longitudinal direction of the at least one ribbon insulating material in the first layer and a corresponding longitudinal direction of the second layer corresponding to twice the winding angle.
Accordingly, the invention is characterized by a first layer of turns that is radially adjacent to a second layer, which can be produced by changing the winding direction by folding the electrical conductor and the at least one ribbon insulating material layer, and in that the total angle, which is produced by the folding, between the longitudinal direction of the ribbon insulating material in the first layer and the corresponding direction of the second layer corresponds to twice the winding angle. One major advantage according to the invention is that the change in the winding direction of the electrical conductor to produce a radially adjacent further layer is not carried out as was previously normal by slowly changing the winding direction, that is to say, continuously, but by folding the electrical conductor. In such a context, the term folding means folding the electrical conductor about a straight imaginary line that extends over the width of the ribbon electrical conductor and the at least one insulating material layer. The winding direction is, accordingly, changed in a discontinuous manner, without any possibility of such stresses occurring in the side areas in the longitudinal direction of the ribbon electrical conductor as those that occurred in the past over a comparatively long longitudinal section of the electrical conductor. However, this also avoids the formation of waves and the tendency towards kinking or deformation. In principle, such an advantage can be achieved with any ribbon conductor.
In a situation where more than one insulating layer is wound together with the electrical conductor to form turns, these may be disposed both on one broad face of the electrical conductor and on both of its broad faces.
In accordance with an added feature of the invention, the turns of each of the first and second layers have a diameter, the electrical conductor has a ribbon width, and the winding angle is a characteristic winding angle selected as a function of the ribbon width and the diameter of the turns of a respective one of the first and second layers.
The risk of the formation of waves or kinks is also particularly high when the characteristic winding angle is less than about 85xc2x0. According to the invention, these described disadvantageous effects are also reliably avoided in this case. The characteristic winding angle is that angle which is chosen as a function of the ribbon width of the electrical conductor and the diameter of the turn of the relevant layer so as to ensure that the individual turns are disposed parallel to one another during the winding process, and such that such undesirable mechanical stresses in the longitudinal direction of the electrical conductor are reliably avoided.
In accordance with another feature of the invention, an insulating layer is inserted between the first layer and the second layer. In this case as well, the invention advantageously avoids the formation of waves or cracks while, furthermore, achieves the advantage of avoiding voltage flashovers between the individual layers and, furthermore, increasing the impulse withstand voltage of the layers.
In accordance with a further feature of the invention, one of the first and second layers has an axial end and the folding is disposed at the axial end.
The winding is developed according to the invention if the fold is disposed at one axial end of a layer. In principle, the electrical conductor can be folded at any axial point, for example, to produce radially adjacent layers, although these should have different axial lengths, or to produce two separate axially adjacent layers, which are disposed radially adjacent to a further layer. However, two adjacent layers are frequently intended to have the same axial length. Then, as proposed according to the invention, the fold is disposed at the axial end of one layer. Such a configuration results in a layer having an optimum active axial length.
In accordance with an additional feature of the invention, the folding has a fold angle of approximately 180xc2x0.
In accordance with yet another feature of the invention, the at least one ribbon insulation material layer is a plurality of ribbon insulation material layers, the folding has an internal area and a folding base, one of the ribbon insulating material layers is introduced at an introduction point into the internal area of the folding starting in a region adjacent the folding base, and the one ribbon insulating material layer is one of applied to the electrical conductor and fitted as ribbon insulating material to the electrical conductor from the introduction point.
In accordance with yet a further feature of the invention, the at least one ribbon insulation material layer is a plurality of ribbon insulation material layers, the folding has an internal area and a folding base, one of the ribbon insulating material layers is introduced at an introduction point into the internal area of the folding starting in a region of the folding base, and the one ribbon insulating material layer is one of applied to the electrical conductor and fitted as ribbon insulating material to the electrical conductor from the introduction point.
In accordance with yet an added feature of the invention, a specific one of the turns has a circumference and the at least one insulating material layer is folded at a point on the circumference of the specific one of the turns different than a point at which the electrical conductor is folded.
With the objects of the invention in view, there is also provided a method of winding one of a transformer and a coil, including the steps of one of fitting at least one ribbon insulation material layer to a ribbon electrical conductor and applying the at least one ribbon insulation material layer as ribbon material to the electrical conductor, winding the electrical conductor and the at least one ribbon insulating material layer to form turns around a winding core along a winding axis with a number of the turns located axially alongside one another forming one layer of at least two radial adjacent layers of turns, individual turns of the winding having a predetermined winding angle with respect to the winding axis of the winding core, and producing a second layer of turns radially adjacent a first layer of turns by changing a winding direction by folding the electrical conductor and the at least one ribbon insulating material layer, a total angle produced by the folding, between a longitudinal direction of the at least one ribbon insulating material layer in the first layer and the corresponding longitudinal direction of the second layer, corresponding to twice the winding angle.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a winding for a transformer or a coil, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.